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Polarographic study of the effect of solvents on the reaction of Na amalgam with some vinyl monomers

1973; Wiley; Volume: 11; Issue: 1 Linguagem: Inglês

10.1002/pol.1973.170110107

1542-9369

Sh. Margel, Moshe Levy,

Chemical Reaction Mechanisms

Abstract Acrylonitrile, methacrylonitrile, ethyl acrylate, anthracene, and Na + were studied polarographically in four solvent media: diglyme, DMSO, 25% H 2 O in diglyme, and liquid NH 3 . Cathodic shifts were observed for Na + and anodic shifts for the vinyl monomers in DMSO, H 2 O and NH 3 . The values of Δ E = ( E 1/2, monomer — E 1/2, Na + ) were used in interpretation of the solvent effects observed previously for the reaction of these monomers with Na amalgam. In diglyme Δ E is very large (0.49 V for MeAN and 0.37 V) for AN, and therefore very slow reaction takes place. In DMSO, MeAN still reacts very slowly (Δ E = 0.23 V), while AN (Δ E = 0.09 V) reacts considerably faster than in diglyme and 100 times faster than MeAN in DMSO. Liquid ammonia brings both MeAN and AN to very low Δ E (0.08 V and −0.05 V, respectively), and both reactions are very fast and yield only the hydrodimers. Water, on the other hand, has a large accelerating effect on the rate, but as it is a proton donor it yields only the reduced products.